1. Field of the Invention
This invention relates to a controlling system for a vehicle-carried internal combustion engine for a vehicle having a power transmitting system for transmitting driving force from the internal combustion engine to a wheel by way of a transmission, and more particularly to a controlling system for such vehicle-carried internal combustion engine which includes controlling means of the drive-by-wire type which can drive a throttle valve disposed in an intake air path of the internal combustion engine to open or close irrespective of an amount of operation of an artificial operating member such as, for example, an accelerator pedal for operating the vehicle-carried internal combustion engine.
2. Desciption of the Prior Art
An automobile includes a power transmitting system for transmitting driving force or power from an internal combustion engine, which may be hereinafter referred to only as engine, to a wheel by way of a transmission. Normally, when the transmission is at such a gear position at which the driving force of the engine is not transmitted from the transmission to the wheel, that is, at a neutral position (N range), or at a parking position (P range) where the transmission is an automatic transmission, the engine must only maintain its idling speed. It is waste of fuel to open the throttle valve greater than a necessary level to cause upwash of the engine.
In a conventional automobile, however, since the throttle valve and accelerator pedal are interconnected by way of a rope or cable member, if the accelerator pedal is operated when the gear position is within, for example, the N range or P range, then the output power of the engine is increased and the speed of the engine is raised in response to such operation, which will lead to waste of fuel.
An improved engine controlling system is disclosed, for example, in Japanese Patent Laid-Open No. 113531/1989 wherein the engine rotational speed is compulsorily controlled to a level lower than a predetermined low speed such as an idling speed when the select lever of an automatic transmission of the automobile is in a non-driving range while the vehicle is in a stopping condition in order to eliminate such disadvantage of a conventional internal combustion engine as described above.
Such engine controlling system is superior in fuel consumption because the engine speed is not raised, when the select lever of the automatic transmission is in a non-driving range during stopping of the vehicle, even if the accelerator pedal is operated. However, reversely speaking, even if the accelerator pedal is operated, the engine will not respond to such operation at all. Such phenomenon will cause the driver to have an unfamiliar feeling, that is, an uneasy feeling to the controlling system and hence is not preferable.
Further, the engine controlling system is applied only to an automatic transmission and effective only when the vehicle is in a stopping condition. Accordingly, the engine controlling system is narrow in application.